1. Technical Field of the Invention
The present invention relates to a printed wiring board having one or more signal lines.
The present application claims priority from Japanese Patent Application No. 2011-027624, filed on Feb. 10, 2011, which is incorporated by reference in its entity and which is to be a part of the description and/or drawings of the present application.
2. Description of the Related Art
Signal lines of a printed wiring board are covered by an insulating layer in general, and it is known that the dielectric tangent of this insulating layer affects the signal loss. Multilayer circuit boards are known which relate to this kind of technique and in which signal lines are surrounded by an air layer in view of achieving high-speed transmission (Japanese unexamined Patent Publication No. H11 (1999)-168279 (Patent Document 1)).